Physiologic insulin levels stimulate glycogen synthase in diploid fibroblasts. The percent maximal stimulation of this activity is being compared to fractional receptor occupancy in fibroblasts from normal and diabetic Pima and Caucasian subjects. This in-vitro measure of the insulin resistance of a specific activity will also be applied to insulin stimulation of (Na ion plus K ion) ATPase, pyruvate kinase and alpha-aminoisobutyrate transport. Fat cells from obese and normal subjects are being sized and compared in terms of the antilipolytic effects of insulin.